Washing installations of the type mentioned above, i.e. washing devices with dishwashers arranged in parallel, have been known for a long time. However, the known constructions suffer from a number of drawbacks. Either the dishwashers must be loaded manually, which is time- and labour-consuming. Moreover staff is required to monitor when the dishwashers have finished, which dishwashers are free etc, which makes this system very inefficient. Experiments with automatic loading systems for this type of installation have been made, but such systems have been very bulky and impractical. As an example, a construction can be mentioned in which the dishwashers are loaded by means of roller conveyors which are arranged in the feeding direction of the dishwashers, in front of and behind each dishwasher. This construction is not only bulky but also makes access to the dishwashers in case of service difficult. Furthermore the roller conveyors, and the floor surface therebelow, are difficult to keep clean, which has a detrimental effect on the hygienic standard of the installation. Separate roller conveyors also require staff to distribute the goods to be washed among the different dishwashers. An advantage of this type of installation with parallel dishwashers, however, is that the remaining dishwashers can be used even if one or more dishwashers need to be serviced or the like.
Most washing installations on the market, however, are of a so-called indexing type, meaning that a dishcarrying trolley is run through a plurality of washing compartments arranged in series. These systems have a number of drawbacks in common. First, the systems are connected in series and in many cases they have a common control for washing and transport. If one part of the installation is put out of service, thus the entire installation comes to a standstill with a capacity loss of 100%. Second, connecting in series means that the consumption of time for each step in the process must be adjusted to the step that requires the largest amount of time, i.e. some fast working processes will stand still for a great part of the time. Finally, the indexing systems have in most cases a covered design, which renders visual monitoring of the washing process as well as service and maintenance difficult. In these respects, parallel systems are preferred, but the previously known systems have the drawbacks mentioned above. Particularly serious problems arise, for example, in washing installations in hospitals, where a clean and hygienic environment is an absolute requirement, and where great demands are placed on washing capacity and operational reliability.